Dispensers for liquids having relatively high viscosities, such as soap, shampoo, tomato ketchup, mayonnaisse or the like, normally take the form of a semi-rigid plastic container having an openable closure cap or a reciprocal dispensing valve mounted thereon. Conventional dispensers of this type are relatively expensive to manufacture, prone to malfunction and normally do not insure that a pre-measured charge of the liquid will be dispensed therefrom.
Other types of conventional dispensers include thin-walled plastic pouches that are heat sealed to retain a liquid product therein. A corner of the pouch is either ripped open to dispense the product or a closure plug is used for this purpose. Further, U.S. Pat. No. 3,009,498 discloses a self-sealing valve for pouches or bags which purportedly exhibits critical ratios whereby the valve will close automatically to seal the bag after product has been dispensed therefrom.